Art of refining hydrocarbon oils



MVM a ATTORNEYS J. WALSKO y May 74, 1940.

ART OF REFINING HYDROCARBON OILS Filed March 2l, 1938A Patented May 7, 1940 John Walsko, Whiting,

Ind., assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine Application March 21, 193s, serial No. 197,062

2 Claims.

This invention relates to improvements in the refining of lubricating oils derived from petroleums. In referring to lubricating oils I refer to oils having a viscosity upwards of 70 secondsl at 100 F. Saybolt Universal. This application is in part a continuation of my co-pending application Serial No. 554,392, filed August 1, 1931.

I have discovered that a number of important advantages, with respect to the product'produced and with respect to the refining process, are secured by subjecting such lubricating oil stocks to treatment with a selective solvent, such as nitrobenzene, and an acid, such as sulphuric acid, phosphoric lacid or acetic acid, at the same time. I'hev treatment of the oil with the solvent and the acid at the same' time secures advantages which are not secured by the useof the solvent alone or by the use of the acid followed by the use' of the solvent or by the use of the solvent followed by the use of the acid.

The advantages of the invention include particularly improvement in the stability of the refined product and improvement in the color of the refined product, and also include improvement of the viscosity index of the reflned product, reduction of the Conradson carbon content of the refined product, and improvement in the demulsibility of the refined product, and, with respect to the reiining process the advantages include particularly improved recovery of the refined oil and also include more rapid and more complete separation of the refined oil from the sludge and associated material. The process is useful generally in the treatment of lubricating oilv stocks derived from Pennsylvania crude petroleum or other Gulf Coast crude petroleum. It is particularly useful in the treatment of pe- 'troleum stocks containing asphaltic impurities.

In carrying out the invention the raw lubricating oil stock is mixed simultaneously with the solvent and with the acid at a temperature below that at which the stock becomes completely miscible with the selective solvent, and the sludge and associated material are thereafter separated from the oil, the latter containing some vdislsolved solvent. The simultaneous presence of the solvent apparently modifies the action ofthe acid to make smaller amounts as effective, as refining agents, as larger amounts in the absence of the solvent, aswell as to afford the advantages previously noted. Thus in the presence of the selective solvent an amount of acid not over approximately 1%, based on the oil, is effective in carrying out the process ofthe present invention. It is desirable that the acid should (ol. 19e-13) be one which does not which is not present in an impurity.

Several embodiments react with the selective solvent under the conditions of working, and

the solvent, as such, as

of the invention employing sulphuric acid as the acid and nitrobenzene as the solvent will be greater detail.

hereinafter .described in The treatment of the raw oil with nitrobenzene and sulphuric acid is advantageously carried out as a succession of repeated treatments.

treatment, or each of l0 The the treatments, may be carried out at temperatures upwards` of about 45` F., as high as 100 of time longer at lower temperatures and shorter at vhigher temperatures F. and 60 minutes at 4 F. or higher, for periods l5 say 3 minutes at 100 5 F., for example. The

oil subjected to treatment may be de-Waxed or partially de-waxed prior to treatment. oil subjected to treatment contains a substantial If the proportion of wax, separation of the sludge and associated material from the oil following the treatment or treatments is usually promoted by effecting the separation at higher .rather than lower temperatures. Following separation of the sludge and associated material from the oil, after the treatment orv the last of a succession ofl treatments, the oil from the rainate layerl is neutralized and dissolved nitrobenzene is separated therefrom. A neutralization may be effected, for example, with an absorbent earth,

with caustic soda, with ammonia or with lime.

Neutralization of the oil by treatment with an absorbent earth is advantageous in the production of a refined oil of good color and bloom.

Following separation of dissolved nitrobenzene, the oil may or may not be filtered through or treated with an absorbent earth, for example.V

The invention4 will be further illustrated by .the following 'examples of various applications o of the invention. It is intended and will be understood that these detailed descriptions of specie applications of the invention are by way of exemplification and that the invention is not limited thereto.

Recovery of used motor oil The original motor oil had a viscosity of '715 ,seconds at 100 F. and 6 8 seconds. at 2107 F., and

portion by volume of nitrobenz of this used oil was treated with ene and 1.8 pounds per barrel of 66 B. sulphuric .acid for 3 minutes at F. and separation of the sludge and associated material from the treated oil was effected at 50 F. The recovered oil had a viscosity of 645 seconds at 100 F. and 68 seconds at 210 F., and a Conradson carbon content of 0.48. Another portion of the used oilwas treated with 50% by volume (on the oil treated in each instance) of nitrobenzene and 2.0 pounds per barrel of 66 B. sulphuric acid for 3 minutes at 100 F. followed by separation at 50 F. in each of two successive treatments. The recovered oil had a viscosity of 580 seconds at 100 F. and 67 seconds at 210 F., and a Conradson carbon content of 0.31. Still another portion of the used oil was treated with 50% by volume of nitrobenzene and 1.83 pounds per barrel of 66 B. sulphuric acid for 3 minutes at 100 F. followed by separation at 50 F. in each of three successive treatments. The recovered oil had a viscosity of 567 seconds at 100c7 F. and 67 seconds tzl" F., and a Conradson carbon content of Lubricating oil distillate from Gulf Coast crude petroleum The raw lubricating oil stock had a viscosity of 748 seconds at 100 F. and 61 seconds at 210 F., and a gravity of 19.3 A. P. I. This raw stock was treated in one instance with 50% by volume of nitrobenzene and 2.5 pounds per barrel of 66 B. sulphuric acid for 15-60 minutes at a temperature of 45 F. followed by separation at 45 F. in each of two successive treatments, and in another instance with 50% by volume of nitrobenzene a-nd 1.25 pounds per barrel of 66 B. sulphuric acid for 15-60 minutes at 45 F. followed by separation at 45 F. in each of four successive treatments. The rened products had Viscosities of 458-489 seconds at 100 F. and 55-58 seconds at 210 F., and gravities of 23.0-25.3

Lubricating oil distillate from Gulf Coast crude petroleum The raw lubricating oil stock had a viscosity of 318 seconds at 100 F. and 47 seconds at 210 F., and a gravity of 20.7 A. P. I. This raw stock was treated with 50% by volume of nitrobenzene and 0.25pound per barrel of 66 B. sulphuric acid for 3 minutes at 100 F. followed by'separation at 45 F. in each of four successive treatments. The rened product had a viscosity of 224 seconds at 100 F. and 46 seconds at 210 F., and a gravity of 26.8 A. P. I.

Lubricating oil stock from Gulf Coast crude petroleum The raw lubricating oil stock had a viscosity of 5850 seconds at 100 F. and 147 seconds at 210 F.

One portion of this raw stock was treated with,

100% by volume of nitrobenzene and 2.5 pounds per barrel of 66 Be'. sulphuric acid for 3 minutes at 100 F. followed by separation at 45 F. in each ozone for 8 hours while maintained at a temperature of '200 F. and then treated With 50% by volume of nitrobenzene and 1.25 pounds per barrel of 66 B. sulphuric acid for 3 minutes at 100 F. followed by separation at 45 F. in each of four successive treatments. The rened product had a viscosity of 1680 seconds at 100 F. and 101 seconds at 210 F.

Klfefineal lubricating oil from Pennsylvania crude petroleum on`ds at 100 F. and 80 seconds at 210 F. a gravity of 29.8 A. P. I. and a Conradson carbon content of 0.364. v

Following the simultaneous treatment with nitrobenzene and sulphuric acid, the sludge andl associated material may be separated from the oil, for example, by settling or by centrifuging. The separation of the sludge and associated material from the oil may bepromoted by including in the sulphuric acid as supplied to the treatment aminor proportion of sodium sulphate, say 5% by weight on the acid for example. The addition of water will sometimes promote the separation of the sludge and associated material from the treated oil, and is useful where the separa-- tion is to be effected at higher rather than lower temperatures. I have observedv that, although the use of an appropriate proportion of sulphuric acid in conjunction with the nitrobenzene promotes rapid separation of the sludge and associated material, an excess of sulphuric acid will sometimes retard this separation. When the treatment with nitrobenzene and sulphuric acid is carried out as a succession of repeated vtreat-v ments,` the separation of the sludge and associated material following'the rst treatment usually proceeds more slowly than following successive treatments. v l

The nitrobenzene used in the treatment may be recovered for re-use almost completely from the sludge and associated material and from the treated oil. For example, it may be distilled from the sludge and associated material and from the treated oil following neutralization Appropriate measures should be taken to avoid decomposition of the nitrobenzene by the formation of aniline; such decomposition can usually be avoided by steam distillation. The nitrobenzene mayalso be recovered for re-usefrom the treated oil containing dissolved nitrobenzene,

l for example, by chilling the oil to a temperature approximating 3540 F. while superposed upon and in direct contact with a body of water. 'This latter procedure is not my invention but is the invention of Arnold C. Vobach.. When the treatment with nitrobenzene and sulphuric acid is carried out as a succession of repeated treatments, the sludge and associated material separated from the oil in later treatments of the series may be utilized, in some cases with Aap-- propriate additions of fresh nitrobenzene and/or fresh sulphuric acid, as thel treating mixture in earlier treatments of the series. Usually the capacity of the treating mixture is consumed much more completely' in the earlier treatments of such a series than in the later treatments.

After separation of the nitrobenzene present from the sludge and associated material, the remainingl sludge and associated material is with advantage reduced to coke to produce an oil distillate peculiarly useful as charging stock for cracking operations intended to produce motor fuel gasoline of high anti-knock value.

I have illustrated in the accompanying drawing, diagrammatically and conventionally, one arrangement of apparatus adapted for carrying `out one embodiment of my invention.

Referring to the accompanying drawing, raw lubricating oil stock, which may have been dewaxed or partially dewaxed, is supplied to the stock tank I. Successive charges of this stock are supplied to the agitator 2 by means of pump 3. With each charge an appropriate amount of sulphuric acid is supplied from the blow-case 4 and an appropriate amount of nitrobenzene or 'of a sludge mixture including nitrobenzene is supplied from the tank 5 or the tank 6, respectively, vby means of pump 3. A mixture of fresh nitrobenzene and such sludge mixture may be supplied to the agitator 2 instead of either alone by means of pump 3. The mixture is agitated in the agitator 2 for the desired period while the desired temperature is maintained,by circulation of a heating medium Vor a cooling medium through the coil 1,. and the mixture is then pumped into one or the other of the settling tanks 8 and 9 by means of pump 3. In .the settling tank a separation is effected while the desired temperature is maintained, by circulation of a heating medium or a cooling medium through lthe coil I0 or II. From the settling tank, 8 or 9, the sludge and associated material is discharged to tank I2 by means of pump I3.

The separated oil, containing some dissolved nitrobenzene, is supplied to the agitator I4 by means of pump I3. Assuming a treatment comprising four successive treatments with nitrobenzene and sulphuric acid, this oil is subjected to three successive treatments with nitrobenzene and sulphuricv acid, or sludge mixture including nitrobenzene and sulphuric acid. followed by separation of sludge and associated material in the agitator I4 while the desired temperature is maintained by circulating a heating medium or a cooling medium through the coil I5. Following each successive treatment, a separation is effected in the agitator and the sludge and associated material is discharged to one of the tanks I6,4 6 or I2 by means of pump I3. On the same assumption, the first separated sludge and associated material may beV discharged to tank I2, the second to -tank 6 and the third to tank I6. 'I'he treating mixture in the first treatment carried out in the agitator vI4 may consist entirely or largely of a .sludge mixture from tank I6. Following the last separation of sludge and associated material in the agitator I4, the treated oil is discharged to the stock tank I' by means of pump I3. This partially refined lubricating oil stock may be subjected to any desired further treatment, including of course separation of dis.- solved nitrobenzene.

This arrangement of apparatus illustrated prostock tank I'I are supplied to the agitator I8 by means of -pump I9. With each charge an appropriate amount of an absorbent earthis supplied from the hopper 20. The mixture is agi- .tated in the agitator I8 for the desired period while the desired temperature is maintained, by circulation'of a heating medium through jacket 2I, and the mixture is then pumped through the filter press 22 by means of pump 23. The oil separated from the earth in the filter press 22 is discharged to the stock tank.24 by means of pump 25. still 26 by means of pump 21 in which still dissolved nitrobenzene is separated from the oil by distillation. The thus recovered nitrobenzene is returned to the tank 5 by rmeans of pump 28. The oil remaining undistilled following separation of the nitrobenzene may be pumped through one' or the other of the percolation filters 29 and 30 byv means of pump 3I to the stock tank 32. The filters 29 and 30 are charged, for example, with an absorbent earth.

The. treatment of the partially refined lubricating oil stock in the agitator I8 may consist,

. for example,` of agitation for 5 minutes at a temperature of 150 F. with 5% by weight of Olmstead earth. A similar treatment, followed by separation of the earth, may be applied to the oil following separation of nitrobenzene in the still 2B instead of percolation filtration. Either or both of these treatments with earth may also be carried out at higher temperatures. Following separation of the nitrobenzene, for example, the oil may be mixed with 5% of Olmstead earth and the mixture maintained at a temperature of 400-500" F. for-30 minutes. Such high temperature earth treatment of the partially refined lubricating oil stock, however, is not my invention but is the invention of Arnold C. Vobach.

The arrangement of apparatus illustrated provides for recovery of nitrobenzene from the sludge and associated material separated following thetreatment or trcatmnts of the oil stock with nitrobenzene and sulphuric acid by neutralization with lime followed by a steam distillation, and for recovery of the oil content of the remaining sludge mixture by reduction to coke. Successive charges of sludge mixture from the tank I2 are supplied tothe agitator 33 by means of pump 34. With each charge an amount of line required to neutralize the charge is supplied from the hopper 35. The neutralized mixture is pumped to the steam still 36 by means of pump This stock is supplied to the steamA 31. Nitrobenzene separated from the sludge mixture by distillation in the still 38 is returned to tank 5 by means of pump 38. 'Ihe residual mixture from the steam still"36 is rediced to cke in the coke still 39, tank 42 and pumps 43 and 44 v being provided for handling this residual mixture. the stock tank 40 by means of pump 4I. 'I'his coke still distillate is peculiarly useful as charging stock for cracking operations intended to produce motor fuel gasoline of high anti-knock value.

The range of proportions, with respect to each other and with respect to the lubricating oil stock being treated, of the nitrobenzene and sulphuric acid simultaneously used in the combined treatment and the concentration of the sulphuric acid, may vary within wide limits. In general. acid concentrations in the range 9398% H1804 are advantageous although more -or less concentrated acid may be used. The total volume of nitrobenzene used may vary from less than 50% f The coke still distillate is discharged to tomore than 400% by volume on the oil. 'I'he l eiciency of the operation is usually improved if the combined nitrobenzene and the sulphuric acid treatment is carried out as a succession of repeated treatments, particularly when sludge and associated material separated from the oil in later treatments of the series is utilized as the treating mixture in earlier treatments of the series. It will be apparent that the proportions of nitrobenzene and sulphuric acid and the concentration of the acid may be varied from step to step in such successive treatments. 'I'he proportion of sulphuric acid used in each treatment may vary, for example, from about 0.1 pound per barrel to as much as 10 pounds or more per barrel of oil treated, v

In some instances, particularly when improvement of the viscosity index of the refined product is important, I have found that oxidation of the lubricating oil stock prior to the combined treatment. with nitrobenzene and sulphuric acid,

as illustrated in 4one of the foregoing examples,

is particularly advantageous.

I claim:

1. The process of treating a petroleum stock containing asphaltic impurities which comprises agitating the stock with a selective solvent in the presence of not over, approximately, 1% of an acid, which does not react vvith` the selective sol-V vent under the conditions of working, and which is not present in the solvent,vas such, as animpurity below the temperature at which the stock becomes completely miscble with the selective solvent, separating thesolvent layer from the' raffinate layer and removing the selective solvent from the rainate layer. 1

2. Process according to claim l in which the acid employed is an inorganic acid.

JOHN WALSKO. 

